Editor's note: Ruben Navarrette Jr. is a nationally syndicated columnist and a member of the editorial board of the San Diego Union-Tribune. Read his column here.

Ruben Navarrette says President Obama shouldn't wait to start building the case for immmigration reform.

SAN DIEGO, California (CNN) -- Obviously, President Obama has a lot on his plate: two wars, an ailing economy, the mortgage crisis and more. But that doesn't relieve him of the obligation to serve up his plan for immigration reform.

Sooner would be better than later. On that point, interestingly enough, you'll find agreement from both sides of the ideological divide. The problem is they don't agree on what "reform" means.

To enforcement-only restrictionists, the phrase "immigration reform" means securing the borders, continuing workplace raids, speeding up deportations of illegal immigrants and limiting the number of legal immigrants.

To immigrant advocates, it means a comprehensive approach that links enforcement, guest workers and earned legalization for some of the 12 million illegal immigrants in the United States.

While squeamish political strategists will tell you that it is never a good time to grab hold of such a thorny issue, Obama has some capital now. He should spend some of it on fixing the broken immigration system.

In doing so, he would avoid repeating a mistake by his predecessor. In one of his final interviews as president, George W. Bush said that he should have pursued immigration reform at the start of his second term instead of tackling the challenging issue of shoring up Social Security.

Besides, the political picture is only likely to get more complicated as the months pass. The more controversial the legislation, the less likely it is to get done in an election year. So if Obama doesn't put a plan on the table this year, it'll push the debate into 2011.

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By then, alliances will have shifted, and Obama might just find himself engaged in more skirmishes with his own party than with the opposition.

That could make it impossible for him to get anything through Congress until his second term, that is, if there is a second term. So if Obama intends to do something on immigration reform, he had better hurry.

The big mystery is what the president intends to do. No one seems to know, and he is not dropping any hints.

Obama campaigned for the Latino vote by portraying John McCain as a flip-flopper who went from co-authoring a comprehensive reform plan to parroting a secure-the-border-first approach and promising to be more consistent as president. And while Obama told three Latino organizations last summer that he intended to make immigration reform a top priority of his administration, early signs are causing worry among some immigration advocates.

First came his choice of Rahm Emanuel as White House chief of staff. While serving as Speaker Nancy Pelosi's lieutenant in the House of Representatives, Emanuel was a major obstacle to an immigration deal. Emanuel called immigration the new "third rail" of American politics, and he thought it belonged on the back burner, if not completely off the stove.

Then, there was Obama's equally tone-deaf decision to name Janet Napolitano to head the Homeland Security Department.

As Arizona governor, Napolitano signed the toughest employer sanction law in the country, hyperbolically declared a "state of emergency" along the U.S.-Mexican border and joined the clownish Maricopa County Sheriff Joe Arpaio in condemning the Homeland Security Department -- the same agency she now heads -- for not doing enough to enforce immigration laws.

Personally, I'm convinced that the answer to America's immigration woes is a middle-of-the-road approach that combines enforcement measures (continued workplace raids, speedier deportations, more spending on tools and technology for border patrol agents, etc.) with guest workers, an increase in legal immigration, a tamper-proof ID card for all U.S. employees, tougher sanctions for employers and a path to earned legalization for illegal immigrants who came into the country before January 1, 2000.

That may be close to what Obama has in mind, and the best way for him to get a plan through Congress would be to make sure he keeps the language on guest workers (to get the votes of Republicans beholden to business) but also creates protections for these workers (to get the votes of those Democrats beholden to labor unions). Above all, he must act quickly.

In a recent interview with National Public Radio, Napolitano spelled out her department's priorities, which included "enforcement of our nation's immigration laws" and taking up the larger issue of immigration reform at "the right time."

Guess what, Mr. President. That time is now

The opinions expressed in this commentary are solely those of Ruben Navarrette.